1. Field of the Invention
The present invention relates to a stump-extracting tool.
2. Description of the Prior Art
It is known that, when felling trees, the tree-stumps have to be destroyed in order to permit earthwork, excavation work or preparation of ground for cultivation of crops.
The most elementary method of tree-stump extraction is to dig right round the stump and then to extract it. However, there are many disadvantages attached to this method. In particular, the operation just mentioned is highly time-consuming and makes it necessary to displace a considerable volume of soil. Furthermore, the tree-stump is finally extracted in one piece and is difficult to destroy by incineration, for example.
In order to circumvent these drawbacks, various stump-extracting tools have already been proposed. One type of tool which is worthy of mention comprises a pivoting blade mounted at the end of an arm opposite to a ledger-plate in accordance with a structure which is similar to that of a very large pair of secateurs. Tools of this type make it possible only to split a tree-stump vertically but do not permit easy extraction of large stump fragments, with the result that they have not led to any practical development.
Another type of stump-extracting tool described in U.S. Pat. No. 4,094,348 comprises a flat spur of substantial length having a cutting edge at one end and provided with a cutter-blade in a plane which is transverse to the plane of the spur. The cutter-blade has a series of teeth which are directed obliquely with respect to the plane of the spur. Tools of this type make it possible to split the stump down to a certain depth and to cut-up part of the stump in much the same manner as a plowshare.
However, by reason of the oblique orientation of the teeth, these tools are subjected to a strong lateral reaction which is sustained by the spur and their structure has to be reinforced in order to withstand the forces developed, thus making tools of this type very cumbersome. In consequence, it is necessary to hitch them to the front end of heavy-duty vehicles which are capable of maneuvering only with difficulty on sloping ground or in marshy terrain.